This invention relates to systems for effecting movement of an object and, in desired applications, sensing the movement of objects, especially of micro-structures.
With recent developments in non-planar lithography, the fabrication of micro-structures, including both three-dimensional mechanical parts and three-dimensional electrical components, has become more readily achievable. See, for example, U.S. Pat. No. 5,106,455 and co-pending application, Ser. No. 816,628, filed Dec. 12, 1991. Such micro-structures are finding use in a variety of areas including medical devices, robotics, navigation equipment, motors and similar equipment. It is oftentimes desired in such applications to cause the controlled movement of very small mechanical parts, such as fibers or filaments, and also to detect the movement of mechanical parts, both the degree or extent of such movement and the direction.
It is an object of the invention to provide systems for effecting movement in micro-structural elements.
It is also an object of the invention to provide systems for detecting or sensing movement of micro-structural elements, including the degree and direction of such movement.
It is a further object of the invention to provide such systems which are especially adapted for effecting movement of micro fibers or micro filaments, and for sensing movement therein.
The above and other objects of the invention are realized in a specific illustrative embodiment of a movement actuator which includes an elongate fiber, and one or more strips of actuable material disposed on the surface of the side of the fiber. The actuable material is responsive to an actuation signal for changing its shape to thereby cause the fiber to move to accommodate the change in shape of the material. An actuation signal generator is also provided for selectively applying actuation signals to the strip or strips of actuable material to cause them to change shape and thereby cause the fiber to move as desired.
The strips of actuable material may be placed lengthwise on the fiber and caused to shorten to thereby cause the fiber to bend. Alternatively, the strips may be placed helically about the fiber and again caused to shorten to thereby cause the fiber to twist. Other patterns for the strips of actuable material may also be provided to cause various kinds of movements of the fiber.
The strips of actuable material may be so-called shape memory alloys which change from one shape to another when external heat or an electrical current which causes heat to be generated internally, is applied thereto. When the heat or electrical current is removed and the internally generated heat dissipates, the strips then return to their original shape. Alternatively, the strips of actuable material may be comprised of bimetals, i.e., two layers of different metals with different coefficients of thermal expansion, so that when heated, the strips are caused to change shape and thereby cause movement of the fiber.
In accordance with one aspect of the invention, the fibers may be made of a piezoelectric material and the strips of actuable material may consist of conductive elements positioned on the side of the fiber so that as voltage signals are applied to the conductive elements, the fiber is caused to bend. Various patterns of conductive elements could be provided to cause bending of the fiber, shortening or lengthening of the fiber, etc.
Alternatively, flexible fibers may be coated with piezoelectric strips so that when voltages are applied to the strip the strips bend and cause the fiber to bend.